LIFE SCIENCEC REVISION Human Reproduction

LIFE SCIENCES GRADE 12 2019 Human Reproduction Life sciences Grade 12 CAPS structured, clear, practical - Helping teachers unlockAREA: KNOWLEDGE the power of NCS Life Processes in Plants and Animals TOPIC 2.1: Reproduction in Vertebrates

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https://ultradeep.co.za Summary of presentation Introduction Structure of Male Reproductive System Structure of Female Reproductive System Main Changes that occur during Puberty Gametogenesis Menstrual Cycle Fertilization and Embryonic Development Implantation and Development Gestation Role of Placenta https://tvetpapers.co.za

https://ultradeep.co.za Introduction: • There are 2 types of reproduction. • These are… 1. Sexual and 2. Asexual reproduction • We are studying reproduction in humans. • Therefore we need to know what is sexual reproduction. • Sexual reproduction is reproduction that occurs with the use of gametes. https://tvetpapers.co.za

https://ultradeep.co.za Introduction: • In humans fertilization occurs during sexual reproduction. • This means a haploid sperm fuses with a haploid egg to form a diploid zygote. • The zygote has 46 chromosomes or 23 pairs of chromosomes therefore it is called diploid. So how many chromosomes does the egg and sperm have? https://tvetpapers.co.za

https://ultradeep.co.za Solution: • The sperm has 23 chromosomes • The egg has 23 chromosomes https://tvetpapers.co.za

https://ultradeep.co.za Introduction: • The zygote then divides by mitosis to produce a large number of identical cells. • All the cells have the same number of chromosomes and identical DNA. • Some of these cells become differentiated. • This means that the cells undergo physical and chemical changes to perform specialized function. • Therefore these cells are adapted for their functions. • This is how the body parts are formed. https://tvetpapers.co.za

https://ultradeep.co.za Introduction: • Therefore the zygote eventually develops into a fully formed adult. • Sexual maturity occur between 11-15. • It is known as puberty. • During puberty meiosis occurs in the male and female reproductive organs to produce the gametes. • Since the gametes are produced by meiosis, each gamete will have a haploid number of chromosomes and each egg or sperm will be genetically different from the other. • Both the egg and sperm have 23 chromosomes each. https://tvetpapers.co.za

https://ultradeep.co.za Introduction: • Therefore when the haploid sperm fuses with the haploid egg a diploid zygote is formed. • The cycle starts over. • Humans show a great deal of variation and for each cell in the body of every human has 46 chromosomes. This is possible because … 1. Meiosis is responsible for halving the chromosome number, thus prevents the doubling effect 2. Meiosis is responsible for variation because it ensures that the sex cells are different from each other. https://tvetpapers.co.za

https://ultradeep.co.za Terminology: TERM: Sexual reproduction DEFINITION: USE IN SENTENCE: is reproduction that occurs Humans undergo sexual with the use of gametes reproduction. https://tvetpapers.co.za

https://ultradeep.co.za Terminology: TERM: Puberty DEFINITION: USE IN SENTENCE: refers to the period during which sexual maturity occurs. https://tvetpapers.co.za

https://ultradeep.co.za Structure of Male Reproductive System • The male reproductive system is made up of… 1. Tubes 2. Glands 3. Organs • Lets look at each of these in some detail. https://tvetpapers.co.za

https://ultradeep.co.za Structure of Male Reproductive System • From the diagram we can see that the male reproductive system is made up of the … 1. Testes 2. Vas deferens, ejaculatory duct, and urethra 3. Seminal vesicles, prostate gland and Cowpers gland 4. The penis. https://tvetpapers.co.za

https://ultradeep.co.za Structure of Male Reproductive System 1. The Testes… • There are a pair of testes. • These are the male sex organ. • They are also referred to as the male gonads. • The testes lies outside the abdominal cavity. • They are covered by a sac-like structure called the scrotum. https://tvetpapers.co.za

https://ultradeep.co.za Structure of Male Reproductive System • Inside each testes there a number of small tubules. • These are called the seminiferous tubules. • The seminiferous tubules are lined by the germinal epithelium. T/S testes https://tvetpapers.co.za

https://ultradeep.co.za Structure of Male Reproductive System • The germinal epithelium is responsible for the production of the spermatozoa (sperms). • The sperms are produced by a process called spermatogenesis. • Specialized cells are found within the T/S Seminiferous tubules seminiferous tubules. https://tvetpapers.co.za

https://ultradeep.co.za Structure of Male Reproductive System • These cells are called the cells of Sertoli. • The cells of Sertoli are rich in glycogen. • Remember glycogen is a form of glucose. • Therefore it is thought that the cells of Sertoli provide the spermatids with nutrients. • We will discuss the spermatids later. • For now know that they eventually develop into the spermatozoa. https://tvetpapers.co.za

https://ultradeep.co.za Structure of Male Reproductive System • Interstitial cells are found between the seminiferous tubules. • These interstitial cells are called the Leydig cells. • The Leydig cells secrete testosterone. • Testosterone is the male sex hormone. T/S seminiferous tubules https://tvetpapers.co.za

https://ultradeep.co.za Structure of Male Reproductive System • Testosterone is responsible for the development of secondary male characteristics during puberty. Some of these secondary male characteristics are… 1. Growth of hair on the face, armpits and pubic areas 2. Deepening of the voice 3. Development of muscles https://tvetpapers.co.za

https://ultradeep.co.za Structure of Male Reproductive System • The spermatozoa that are produced in the seminiferous tubules, are stored for a short while in the epididymis. • The epididymis is a coiled tube that lies outside the testes but within the scrotum. • From the epididymis the sperms pass into the vas T/S testes deferens. https://tvetpapers.co.za

https://ultradeep.co.za Structure of Male Reproductive System vas • The deferens is also known as the sperm duct. • The vas deferens or sperm ducts carry the sperm from the epididymis to the ejaculatory duct. • From the diagram we can see that there are 2 ejaculatory ducts. Diagram of Male Reproductive System https://tvetpapers.co.za

https://ultradeep.co.za Structure of Male Reproductive System • The ejaculatory ducts joins the urethra just after it leaves the bladder. • The ejaculatory duct is made up of muscular walls. • The ejaculatory duct carries the sperm together with its secretion. • The sperms together with the secretion of the various glands it passes is called semen. • When the muscular wall of the ejaculatory ducts contract the semen is forced through the urethra. https://tvetpapers.co.za

https://ultradeep.co.za Structure of Male Reproductive System • The urethra is a common tube for both semen and urine. • It runs from the bladder to the exterior. • It runs through the penis. • As the sperm travels through the vas deferens and ejaculatory ducts it passes the accessory glands. Diagram of Male Reproductive System https://tvetpapers.co.za

https://ultradeep.co.za Structure of Male Reproductive System • The accessory glands are the Cowpers gland, the seminal vesicles and the prostate glands. • These glands pour their secretions into the vas deferens and ejaculatory duct. • Collectively the fluid that is secreted has 2 functions. Diagram of Male Reproductive System https://tvetpapers.co.za

https://ultradeep.co.za Structure of Male Reproductive System These 2 functions are… 1. Promotes the movement of the sperm 2. Provides the sperm with nutrients. • The penis is the external male reproductive organ. • It is made up of spongy tissue. • The penis becomes erect when the tissue fills with blood. • This occurs before the penis is inserted into the vagina. • The function of the penis is to transfer the semen to the female. https://tvetpapers.co.za

https://ultradeep.co.za Something for you to do: A Study the diagram of the male reproductive system below. B 1.4.1 Write down the LETTER (A to G) and the NAME of the following: C (a) The part where meiosis takes place (b) The part that transports D semen and urine to the F outside of the body (c) The part where immature sperm cells are stored E https://tvetpapers.co.za

https://ultradeep.co.za Something for you to do: 1.4.2 Name the male hormone A that is responsible for the B development of secondary sexual characteristics during puberty. C 1.4.3 Write down the LETTER (A to G) of the following: G (a) The part where the D hormone mentioned in QUESTION 1.4.2 is F E produced (b) The part which is cut surgically during male sterilization. https://tvetpapers.co.za

https://ultradeep.co.za Solution: 1.4.1 (a) F testis/seminiferous tubules (b) C urethra (c) D epididymis 1.4.2 Testosterone 1.4.3 (a) F (b) B https://tvetpapers.co.za

https://ultradeep.co.za The female reproductive system is made up of the following structures… 1. A pair of ovaries 2. The fallopian tube or oviduct 3. The uterus Structure of Female reproductive System 4. Vagina 5. The vulva Now lets look at each of these structures. The female reproductive system https://tvetpapers.co.za

https://ultradeep.co.za Structure of Female productive System 1. The Ovaries… • There are a pair of ovaries. • These are the female gonads. • They are found in the lower abdomen. • They are held in position by ligaments. • They are responsible for the production of eggs or ova. The female reproductive system https://tvetpapers.co.za

https://ultradeep.co.za Structure of Female productive System • Each ovary is lined with the germinal epithelium. • The germinal epithelium produces the follicles. • The follicles produce the egg or ova by a process called oogenesis. • The follicles also secrete 2 hormones. Ovary showing development of egg https://tvetpapers.co.za

Structure of Female productive System • These 2 hormones are called… 1. Oestrogen 2. Progesterone • These hormones are responsible for secondary female characteristics. The secondary female characteristics are… 1. Increase in the size of breasts 2. Development of pubic hair and hair in the armpits 3. Menstruation

Structure of Female productive System 2. The Fallopian Tubes • There are 2 fallopian tubes. • They lead from the ovary to the uterus. • They transport the egg from the ovary to the uterus. The female reproductive system

Structure of Female productive System 3. The Uterus… • The uterus is a hollow pear shaped organ. • It has thick muscular walls. • The lining of the uterus is called the endometrium. The female reproductive system

Structure of Female productive System • The neck of the uterus is called the cervix • The embryo is attached to the wall of the uterus. • The uterus is leads to the vagina. 4. The Vagina… • The vagina is also called the birth canal. The female reproductive system

Something for you to do: The diagram below shows the structure of the female reproductive system. Give the A LETTER and NAME of: 1.4.1 The part that breaks down when the levels of progesterone and oestrogen drop 1.4.2 The part that plays a role during copulation C B 1.4.3 The part where the zygote will be formed D 1.4.4 The part where the Graafian follicles develop

Solution: 1.4.1 C – Endometrium 1.4.2 D – Vagina 1.4.3 A – Fallopian tube 1.4.4 B – Ovary

Structure of Female productive System • The vagina receives the semen during copulation. • The vagina leads to the outside via an opening. • This opening is called the vulva.

Main Changes that occur during Puberty • As mentioned earlier puberty is the period during which sexual maturity occurs. • It usually occur between 11 to 15 years of age. • However these ages are just averages. • Everyone reaches puberty at a different age. • Puberty can occur as early as 9 or as late as 19 years old. • In females puberty starts between 10 or 11 and usually is completed by 15 to 17 years of age. • While in males puberty can begin between ages 11 to 12 and is completed by the ages 16 to 17 years of age.

Main Changes that occur during Puberty Lets look at some of the changes that occur in both males and females during puberty. Males: 1. Development of pubic hair, this is the growth of hair around the scrotum. 2. Growth of hair in the armpits and on the face. 3. Deepening of the voice 4. Development of muscles and broadening of the shoulders.

Main Changes that occur during Puberty Females: 1. Growth of pubic hair, this is hair around the vagina. 2. Growth of hair in armpits. 3. Increase in the size of the breasts. 4. Onset of menstruation.

• Gametogenesis refers to the process by which gametes are produced from the germinal epithelium Gametogenesis of the male and female gonads or sex organs. • There are 2 types of gametogenesis . These are… 1. Spermatogenesis 2. Oogenesis • Spermatogenesis is process by which the spermatozoa are produced from the germinal epithelial of the testes.

Gametogenesis • Oogenesis is the process during which the eggs or ova are produced from the germinal epithelium of the ovary. Now lets look at each of these processes. Spermatogenesis… Spermatogenesis occur in the following way… • The cells of the germinal epithelium lining the seminiferous tubules divide by meiosis. • Each cell divides to form 4 haploid cells.

Gametogenesis • Each haploid cell is called a spermatid. • The spermatids then matures to form spermatozoa. Structure of Spermatozoa • Remember that the spermatozoa are also called sperms. • Each sperm is made up of 3 parts. These 3 parts are the… 1. Head 2. Middle piece and 3. Tail

Gametogenesis • The head is made up of a nucleus. • The nucleus has 23 chromosomes. • These are 22 autosomes and a gonosome which maybe X or Y. • The head also contains the acrosome. • The acrosome has an A Sperm enzyme that plays a role in penetrating the ovum.

Gametogenesis • The middle piece has a large number of mitochondria. • The mitochondria contains mitochondrial DNA. • The mitochondria provides energy for movement of the sperm. • The tail is long and is A Sperm used for swimming.

Gametogenesis • A common question asked here is to draw and label the sperm. • Please learn to draw and label the sperm. Remember by drawing an learning the labels you will be able to describe the structure of the sperm to!!!

Gametogenesis Oogenesis: • Oogenesis is the process during which the germinal epithelium of the ovary gives rise to the egg or ovum. The process occurs as follows… 1. The germinal epithelium of the ovary produces a large number of follicles. 2. The follicles are produced as a result of mitosis. 3. A single cell inside the follicle enlargens.

Gametogenesis 4. The enlargened cell undergoes meiosis. 5. Therefore 4 haploid cells are produced. 6. Only one cell survives. 7. This cell develops into a mature ovum or egg.

Terminology: TERM: Gametogenesis DEFINITION: USE IN SENTENCE: refers to the process by which Both eggs and sperms are gametes are produced from produced by types of the germinal epithelium of the spermatogenesis. male and female gonads or sex organs.

Terminology: TERM: Spermatogenesis DEFINITION: USE IN SENTENCE: is process by which the Spermatogenesis gives rise to spermatozoa are produced the sperms from the germinal epithelial of the testes.

Terminology: TERM: Oogenesis DEFINITION: USE IN SENTENCE: is the process during which the Oogenesis results in the eggs or ova are produced from formation of eggs. the germinal epithelium of the ovary.

Menstrual Cycle • The menstrual cycle refers to the changes that occur in the ovary and uterus of a female over a period of 28 days. • The menstrual cycle is actually made up of 2 cycles. These 2 cycles are the… 1. Ovarian cycle and 2. Uterine cycle. Lets look at each of these cycles.

Menstrual Cycle The Ovarian Cycle: • The ovarian cycle describes the changes that occur within the ovary during the development of the egg within the Graafian follicle. • The ovarian cycle is controlled by 2 hormones. • These 2 hormones are the follicle stimulating hormone and the luteinising hormone.

Menstrual Cycle • The follicle stimulating hormones is also known as the FSH. • The FSH is produced by the hypophysis or pituitary gland. • The FSH is responsible for the development of a large sac like structure called the Graafian follicle. • The germinal epithelium gives rise to the follicles. • One follicle develops into large follicle called the Graafian follicle.

Menstrual Cycle • The egg or ovum is found within the Graafian follicle. • The Graafian follicle then secretes a hormone called oestrogen. • The oestrogen is involved in preparation of the uterus for pregnancy. • This is achieved by making the endometrium… a. Thicker b. Having an increased supply of blood vessels c. More glandular

Menstrual Cycle • After about 14 days the Graafian follicle raptures to release an egg. • This process is called ovulation. • Ovulation is the process during which the mature egg is released from the Graafian follicle. • The funnels of the fallopian tube collects the egg. • The ruptured Graafian follicle becomes the corpus luteum. • The conversion of the ruptured Graafian follicle into the corpus luteum is controlled by a hormone.

Menstrual Cycle • This hormone is called the luteinising hormone. • This hormone is produced by the pituitary gland. • The corpus luteum secretes a hormone. • This hormone is called progesterone. • The function of progesterone is to maintain pregnancy. • If fertilization does not occur the corpus luteum breaks down.

Menstrual Cycle • Then progesterone is no longer secreted. • The unfertilized egg then leaves the body by a process called menstruation. The Uterine Cycle and Menstruation: • The uterine cycle refers to the changes that occur in the walls of the uterus as it thickens until menstruation occurs. • If the egg is fertilized then the corpus luteum continues to produce progesterone.

Menstrual Cycle • Progesterone ensures that the egg remains attached to the uterine wall. • In other words progesterone maintains pregnancy. BUT… • If fertilization does not occur then the corpus luteum ruptures. • Then the secretion of progesterone stops. • Then menstruation occurs.

Menstrual Cycle • Menstruation refers to the discharge of blood and other material from the lining of the uterus at intervals of about one month. • Menstruation starts during puberty between 11 to 14 years. • But in some females may start as early as 9 years of age but other females may start as late as 21 years of age. • Menstruation occurs 14 days after ovulation. • Menstruation lasts between 5 to 7 days.

Menstrual Cycle • The new ovum is then released 14 days after menstruation. • When a female stops menstruating, this means that the ovaries no longer produce the eggs this is known as menopause. • Menopause occurs between ages 45 and 55.

Menstrual Cycle Here is another way to look at the menstrual cycle. • The first day of the menstrual bleed is the start of the menstrual cycle. • The menstrual bleed may last between 5 to 7 days. • The menstrual bleed is also called a period. • About 14 days later the egg is released from the Graafian follicle. • This process is called ovulation. • The egg is captured by the funnels of the fallopian tube.

Menstrual Cycle • The ruptured Graafian follicle is converted to the corpus luteum. • This conversion is controlled by the luteinising hormone. • The corpus luteum is responsible for the secretion of the hormone progesterone. • The progesterone is responsible for maintaining pregnancy. • But if fertilization does not occur then the corpus luteum ruptures. • No progesterone is released.

Menstrual Cycle: • Therefore unfertilized egg together with the blood vessels will leaves the body through the vagina. • This process is called menstruation. To summarize… • The ovarian cycle describes the formation of the ovum within the ovary until it is released and the corpus luteum is formed. • The uterine cycle describe the changes that occur in the uterine wall as the body prepare itself for pregnancy. • Both the ovarian and uterine cycle makes up the menstrual cycle.

Menstrual Cycle: • The hormones progesterone and oestrogen are involved in maintaining pregnancy. • The hormones FSH and LH controls the menstrual cycle. We have discussed the menstrual cycle a number of times and a number of different because it is so difficult to understand. Hopefully you will find something you understand here!

Something extra • Now lets look at some graphs that show us the relationship between the different cycles and the hormones that are a part of the menstrual cycle.

Something extra: The graph alongside shows use the following… 1. Changes in the endometrium 2. The changes in the levels of the 4 hormones, and 3. The development of the egg.

Something extra: If we start with the endometrium, we can make the following observations… 1. Menstruation lasts between day 1 to 4, it is recognizable by the drops seen on the graph.

Something extra: 2. At this point we find that levels of FSH start to increase and then peaks just before ovulation because it is responsible for the production of the follicles. 3. The LH and FSH peak around the same time, that is just before ovulation.

Something extra: 4. Then ovulation occurs on day 14. 5. Then the endometrium starts to thicken after day 14. 6. Look at the levels of oestrogen you see that it peaks just before ovulation and is responsible for the thickening of the endometrium.

Something extra: 7. On day 14 the levels of LH is high, since ovulation occurs and it is responsible for converting the Graafian follicle into the corpus luteum.

Something extra: 8. Look at the ovarian cycle, you seen that the corpus luteum is produced around day 16 and the level of the hormone progesterone has peaked because the corpus luteum secretes progesterone.

Something extra: 9. From the graph we can see that this female is not pregnant. 10. This is because the corpus luteum disintegrates, levels of progesterone decrease and the lining of the endometrium decreases. 11. Also note that when the levels of oestrogen and progesterone are high the levels of FSH and LH are low.

Something extra: 11. This is the reason why a woman does not menstruate when she is pregnant. 12. Also note that when the levels of oestrogen and progesterone are high the levels of FSH and LH are low. • It is extremely important to understand these graphs because many questions come out on this. • Lets look at some examples.

Something for vou to do: 2.3 Study the graph below of a menstrual cycle and the influence of the different hormones on it. levels Pituitary/ F LH —/ hypophysis FSH ? Hy hormone Growth of follicle |, gy > ene! ee > => o> . oestrogen al > progesterone Ovarian oe a v7 hormone levels . x - a endometrium 1 wa =-pape-e=7-4- Thickness of a uterine lining/ R Oo Hormonal regulation of the female reproductive cycle 2.3.1 2.3.2 2.3.3 2.3.4 2.3.5 On which day does ovulation take place? Between which days does menstruation take place? State ONE function of FSH during the menstrual cycle. Describe the functional relationship between progesterone and FSH. Account for the change in the thickness of the endometrial lining between day 14 and day 21. Did fertilisation take place within the 28-day cycle illustrated in the graph? Give TWO reasons for your answer to QUESTION 2.3.6. 1) (1) (1) (2) (2) (1) (2) (10)

Solution: 2.3.1 Day 14/15 2.3.2 Day 0–6/day 0–7 2.3.3 Stimulates follicle/ovum development in the ovary/secretion of oestrogen 2.3.4 An increase in progesterone level inhibits the release of FSH OR FSH stimulates the development of the ovum and progesterone prepares for implantation when this ovum is fertilized

Solution: 2.3.5 Corpus luteum- starts to secrete progesterone which thickens the lining of the uterus wall/endometrium 2.3.6 No 2.3.7 Corpus luteum has degenerated Progesterone level has decreased FSH level starts to rise LH level decreases

Terminology: TERM: Menstrual cycle DEFINITION: USE IN SENTENCE: refers the changes that occur in The menstrual cycle lasts about the ovary and uterus of a 28 days. female over a period of 28 days.

Terminology: TERM: Ovulation DEFINITION: USE IN SENTENCE: is the process during which the During ovulation a mature egg mature egg is released from is released from the ovary. the Graafian follicle of an ovary.

Terminology: TERM: The uterine cycle DEFINITION: USE IN SENTENCE: refers to the changes that During the uterine cycle the occur in the walls of the uterus walls of the uterus thickens in as it thickens until preparation for pregnancy. menstruation occurs.

terminology: TERM: Menstruation DEFINITION: USE IN SENTENCE: During menstruation the refers to the discharge of unfertilized egg together with blood and other material from the thickened lining of the the lining of the uterus at uterus is released. intervals of about one month.

• Sexual intercourse fertilization and Embryonic is also known as copulation. Development • During copulation the sperms are deposited into the vagina. • The spermatozoa swim up the uterus, into the fallopian tube. Development of fertilized egg

fertilization and Embryonic Development • If the egg or ovum is present in the fallopian tube, the sperm will penetrate the egg. • This process is known as fertilization. • Fertilization results in Development of fertilized egg the formation of a diploid zygote.

fertilization and Embryonic Development • The zygote contains 46 chromosomes with genetic material from both the paternal and maternal parent. • This is because the sperm is of paternal origin and the egg is of maternal origin. • The zygote then divides by mitosis many times asDevelopment of fertilized egg it passes through the fallopian tube.

implantation and Development • It eventually forms a hollow ball of cells called a blastocyst. • The blastocyst develops into the embryo by the time it reaches the uterus. • The embryo then becomes attached to the wall of the uterus. • This process is called Development of fertilized egg implantation.

implantation and Development • The uterine wall has to be thickened, vascular and glandular in order for implantation to occur. • Oestrogen ensures that the endometrium is thickened. • Since fertilization has occurred, the corpus luteum secretes progesterone. • Progesterone ensures that the pregnancy is maintained, by ensuring that the embryo remains attached to the uterine wall.

Terminology: TERM: Blastocyst DEFINITION: USE IN SENTENCE: Is a hollow ball of cells that is The blastocyst becomes implanted in the uterus. implanted into the uterine wall during implantation.

Gestation: • Pregnancy is also called the gestation period. • They both may be defined as a period during which the embryo develops within the uterus until the baby is born. Now lets look at the development of the embryo. 1. 14 Days after Fertilization • The embryo still looks like a big dot. • It is about 1 mm in diameter. Embryo at 14 days

Gestation: 2. 4 weeks old… • The embryo is comma- shaped. • It is about 5mm in diameter. • The head, eyes and ears start to develop. Embryo at 4 weeks • A brain begins to develop within the head.

Gestation: 3. 12 weeks… • Now the embryo resembles a human. • It is about 75mm in length. • It has a mass of about 30g. • The embryo at 12 weeks is called a foetus. Foetus at 12 weeks

Terminology: TERM: Pregnancy or gestation period DEFINITION: USE IN SENTENCE: are both defined as a period Pregnancy of gestation in during which the embryo humans may last up to 9 develops within the uterus months. until the baby is born.

Terminology: TERM: Foetus DEFINITION: USE IN SENTENCE: Name give to the embryo when Once the embryo reaches 12 it reaches 12 weeks. weeks, it is now called a foetus.

Role of Placenta: • Once implantation occurs, the blastocyst develops 2 membranes around itself. • These membranes are found around embryo, therefore they are called the extra-embryonic membranes. • The extra-embryonic membranes are … 1. The Chorion and 2. The Amnion Lets look at each of these membranes…

Role of Placenta: 1. The Chorion… • The chorion is the outmost membrane. • It forms the chorionic villi. 2. The Amnion… • It is found on the inside of the chorion. • It forms a cavity called the amniotic cavity.

Role of Placenta: • The amniotic cavity is filled with a fluid. • This fluid is called the amniotic fluid. Lets look at the functions of the amniotic fluid… 1. It acts as a shock absorber, thus protecting the embryo from mechanical injury.

Role of Placenta: 2. It prevent the foetus from drying out. 3. Maintains a temperature range with a very small change (small range)for the embryo. 4. Allows for the free movement of the foetus.

Role of Placenta: • The placenta is made up of the chronic villi and the uterine tissue in which the villi are embedded. The functions of the placenta are as follows… 1. Attaches the foetus to mother. 2. Allows for the diffusion of dissolved food, as well as oxygen from mother to foetus.

Role of Placenta: 3. It allows for the diffusion of nitrogenous waste from the foetus to the mother. 4. It also allows for the diffusion of the carbon dioxide from the foetus to the mother. 5. It secretes its own progesterone after 12 weeks of pregnancy. • The placenta is attached to the embryo by means of the umbilical cord. • The umbilical cord is a hollow rope like tube. • The umbilical blood vessels are found within the umbilical cord.

Role of Placenta: • These blood vessels are the… 1. Umbilical artery 2. Umbilical veins • The umbilical artery carries deoxygenated blood with nitrogenous waste from the foetus to the placenta, while the… • Umbilical vein carries blood rich in oxygen and food from the placenta to the foetus.

Role of Placenta: • Blood filled spaces develop in the placenta as the foetus develops. • These blood filled spaces are called maternal sinuses. • The chronic villi extend into these sinuses. • This means that the chronic villi are bathe by the blood in the maternal sinuses. • Therefore the blood of the mother and the foetus are in close contact with each other. • But the blood is separated by the walls of the chronic villi, therefore there is no direct contact between the mother’s blood and the foetus’s blood.

Terminology: TERM: Chorion DEFINITION: USE IN SENTENCE: Refers to the outmost The chorion is one of the extra- membrane around the embryo embryonic membranes secreted by the embryo.

Terminology: TERM: Amnion DEFINITION: USE IN SENTENCE: Refers to the membrane found The amnion is an example of on the inside of the chorion. another extra-embryonic membrane

Contraceptives: • Contraceptives are used to prevent pregnancies. Lets look at some contraceptives. 1. Condom • The condom acts as a barrier. • It prevents the sperms from getting into the vagina. • Not only does it prevent unwanted pregnancies, it also provides protection against STDs. Condoms

Contraceptives: 2. Loop • This is also called an IUD. • That it is an intra uterine device. • It functions to prevent the attachment of the egg or embryo to the uterine wall. Intra-uterine device

Contraceptives: 3. Female Condom • Like the male condom it acts as a barrier. • It prevents the sperms from entering the uterus or fallopian tube. Female Condom

Contraceptives: 4. Diaphragm • This device covers the cervical opening. • Therefore it acts as a barrier. • Therefore prevents the sperm from entering the uterus. Diaphragm

Contraceptives: 5. Contraceptive Pill • It contains synthetic hormones . • These hormones prevents the production of the egg. Contraceptive Pills

Contraceptives: 6. Spermicides • These have a chemical substance. • The chemical substance kills the sperm. • It prevents the sperm from entering the cervix. • Therefore it acts as a Spermicides barrier.

Contraceptives: 7. Contraceptive Injections • They contain hormones. • Progesterone or a combination of oestrogen and progesterone. • It functions to stop ovulation. Contraceptive Injection • It works for about 2 to 3 months.

Contraceptives: 8. Male sterilization • This is also known as vasectomy. • The sperm ducts or vas deferens are cut and tied. • Therefore the semen Vasectomy in Males does not contain any sperm.

Contraceptives: 9. Female Sterilization • This is also called tubal ligation. • This is a surgical procedure. • The fallopian tubes are cut and tied. • This prevents Tubal Ligation fertilization of the egg.

Contraceptives: 10.Withdrawal • This is not a reliable method of contraception!!!! • Here the penis is withdrawn from the vagina before ejaculation. • This method is most unreliable!!!!

Contraceptives: 11.Rhythm • In this method the menstrual cycle is used. • Sexual intercourse is avoided a few days before and after ovulation. • Therefore no sexual intercourse between days 10 to 18 of the menstrual cycle. • This is not a reliable method because ovulation is not predictable.

Terminology: TERM: Contraceptives DEFINITION: USE IN SENTENCE: used to prevent pregnancies. The condom is an excellent form of contraception because it also provides protection against STDs.

Terminology: • Sexual reproduction: is reproduction that occurs with the use of gametes. • Puberty: refers to the period during which sexual maturity occurs. • Gametogenesis: refers to the process by which gametes are produced from the germinal epithelium of the male and female gonads or sex organs. • Spermatogenesis: is process by which the spermatozoa are produced from the germinal epithelial of the testes. • Oogenesis: is the process during which the eggs or ova are produced from the germinal epithelium of the ovary.

Terminology: • Menstrual cycle: refers the changes that occur in the ovary and uterus of a female over a period of 28 days. • Ovulation: is the process during the mature egg is released from the Graafian follicle of an ovary. • Uterine cycle: refers to the changes that occur in the walls of the uterus as it thickens until menstruation occurs. • Oestrogen: secreted by the Graafian follicle and is responsible for thickening of the endometrium. • Endometrium: lining of uterus. • Menstruation: refers to the discharge of blood and other material from the lining of the uterus at intervals of about one month.

Terminology: • Blastocyst: is a hollow ball of cells that is implanted in the uterus. • Pregnancy or gestation period: refers to a period during which the embryo develops within the uterus until the baby is born. • Foetus: name give to the embryo when it reaches 12 weeks. • Chorion: is the outmost membrane around the foetus. • Amnion: refers to the membrane found on the inside of the chorion. • Contraceptives: are used to prevent pregnancies.

QUESTION 1 1. Which one of the following represents the correct order of the parts through which spermatozoa pass? A. Testis → vas deferens → epididymis → ureter B. Vas deferens → seminal vesicles → ureter → urethra C. Testis → epididymis → vas deferens → urethra D. Vas deferens → prostate gland → urethra → ureter

QUESTION 2 2. During oogenesis 4 haploid cells are formed. How many of these haploid cells develop into an ovum/ova A. 4 B. 2 C. 3 D. 1

QUESTION 3 3. The statement below refers to the action of different contraceptive methods. 1. inhibits secretion of FSH 2. Increases the level of hormone progesterone 3. Stops the embryo from implanting in the uterus 4. Stops ovulation by inhibiting the development of the follicle Which combination refers to the action of the oral contraceptive pill only… A. 1, 2 and 3 only B. 1, 2 and 4 only C. 1, 2, 3 and 4 D. 2, 3 and 4 only

QUESTION 4 4. Process by which the germinal epithelium of the ovary produces the female gamete is… A. Gametogenesis B. Oogensis C. Spermatogenesis D. None of the above

QUESTION 5 5. Process during which gametes are produced by the germinal epithelium of the gonads. A. Gametogenesis B. Oogensis C. Spermatogenesis D. None of the above

QUESTION 6 6. The process during which the sperms are produced from the germinal epithelium of the testes is… A. Gametogenesis B. Oogensis C. Spermatogenesis D. None of the above

QUESTION 7 7. The cell stage that is implanted during implantation… A. 2 cell stage B. 4 cell stage C. 8 cell stage D. 16 cell stage

QUESTION 8 8. The process during which the glandular and vascular endometrium and unfertilized egg leaves the body is… A. Menstruation B. Ovulation C. Fertilization D. Both A and B

QUESTION 9 9. The process that would not occur when one of the gametes pass the fallopian tube is… A. Menstruation B. Ovulation C. Fertilization D. Both A and B

QUESTION 10 10.The release of the mature egg from the ovary is… A. Menstruation B. Ovulation C. Fertilization D. Both A and B

QUESTION 11 11.The menstrual cycle is made up of… A. Ovarian cycle only B. Uterine cycle only C. Both A and B D. None of the above

QUESTION 12 12.When the Graafian follicle is converted into the corpus luteum, the levels of… A. Progesterone and LH increase B. Progesterone and LH decrease C. Progesterone increases and LH decreases D. Progesterone decrease and LH increases

QUESTION 13 13.The hormone that triggers the formation of the egg during oogenesis is… A. LH B. FSH C. Progesterone D. Oestrogen

QUESTION 14 14.The hormone that is responsible for the secondary female characteristics is… A. LH B. Oestrogen C. Progesterone D. Both B and C

QUESTION 15 15.Specialized cells in the seminiferous tubules, that are rich in glycogen… A. Sertoli cells B. Cells of Leydig C. Interstitial cells D. Epithelial cells

QUESTION 16 16.Interstitial cells found between the seminiferous tubules that secrete the male hormone is… A. Sertoli cells B. Cells of Leydig C. Interstitial cells D. Epithelial cells

QUESTION 17 17.The layer of the uterus that leaves the body during menstruation is… A. Endometrium B. Cervix C. Fallopian tube D. egg

QUESTION 18 18.That gland that secretes both FSH and LH is… A. adrenal B. Thyroid C. Pituitary D. Pancreas

QUESTION 19 19.The hormone that maintains pregnancy is… A. LH B. FSH C. Oestrogen D. Progesterone

QUESTION 20 20.Blood vessel that carries deoxygenated blood away from foetus is… A. Umbilical artery B. Umbilical vein C. Both A and B D. None of the above

SOLUTION: 1. C 11. C 2. D 12. A 3. A 13. B 4. B 14. D 5. A 15. A 6. C 16. B 7. D 17. A 8. A 18. C 9. C 19. D 10. C 20. A